The morpho‐textural signature of large bedforms in ephemeral gravel‐bed channels of various planforms

Abstract

This study adopts a fresh approach to find the similarities between river planforms in contrast to many previous studies that have presented distinguishing characteristics and thresholds. This new approach links textural and morphological attributes of bedforms, termed morpho‐texture, with process and hydrological regime thereby indicated. The study was carried out in depositional features of ephemeral rivers having a range of planforms and located in the Judean Desert. High‐resolution terrestrial laser scanning was undertaken to extract morphological and textural (roughness) characteristics. Results strongly indicate that bars are statistically coarser grained than the adjacent thalweg or anabranches where depositional processes occur. This suggests universal processes within ephemeral rivers regardless of their planform, where rapid flow recession causes the coarse tail of the bedload to be deposited as bars whereas the finer fractions deposit in the thalweg and thereby prevent the development of bed armour.

Geomorphological effectiveness of floods to rework gravel bars: Insight from hyperscale topography and hydraulic modelling

“…Photographic or 'photosieving' methods include those that analyse image texture using semivariograms (Carbonneau et al, 2004;Verdú et al, 2005;Black et al, 2014), analyse image intensity by autocorrelation (Rubin, 2004;Barnard et al, 2007), identify individual grains (Graham et al, 2005), and use Fourier-optics principles (Buscombe and Rubin, 2012). Alternative approaches have used high-resolution digital elevation models (DEMs) from terrestrial laser scanning (TLS; Heritage and Milan, 2009;Hodge et al, 2009;Brasington et al, 2012;Baewert et al, 2014;Schneider et al, 2015;Storz-Peretz and Laronne, 2018) and Structure-from-Motion surveys (Westoby et al, 2015;Vázquez-Tarrío et al, 2017;Woodget and Austrums, 2017) to derive relationships between topographic roughness (i.e. the vertical variation in elevation) and grainsize.…”

An Attempt to Take Into Account Natural Variability in 1D Bedload Prediction

“…In this regard, the recent development of new high‐resolution topographic methods has exponentially increased our capacity for spatially distributed characterizations of topography (Wheaton et al., 2015) and grain size in gravel rivers (Vazquez‐Tarrio et al., 2017). These methods provide new clues for the analysis of reach‐scale spatial variability in the topographic and grain‐size parameters needed for sediment‐transport modeling (see, for example, Storz‐Peretz and Laronne (2013, 2018)).…”

Dynamics of Dual‐Mode Bedload Transport With Three‐Dimensional Alternate Bars Migration in Subcritical Flow: Experiments and Model Analysis

“…Numerous studies have shown that bedload particles' moving and resting states have significant associations with the surface structure of the riverbed (Pyrce & Ashmore, 2005; Storz‐Peretz & Laronne, 2018). The bedload transport behavior is closely related to the bedform.…”